The Bush administration says Cuba is undergoing a de facto political transition while President Fidel Castro recovers from surgery and that it is up to the Cuban people to decide the future of their country. The State Department's top official for Latin America held a press briefing Wednesday.

Assistant Secretary of State for Western Hemisphere Affairs Tom Shannon says the United States is watching developments in Cuba with particular interest since President Fidel Castro temporarily ceded power to his brother, Raul, more than three weeks ago.

"We believe that what we are seeing in Cuba today is effectively a slow-motion transfer of power," he said. "That Fidel Castro, given his age and given the kind of health crisis he went through, does not appear, at least, to be in a position to return to the day-to-day management of affairs that he had effectively enjoyed for so many decades."

Fidel Castro turned 80 last week, and Cuban officials marked the occasion by releasing photographs of the president, the only solid evidence up to that point that Mr. Castro was alive.

Shannon says, while Cuba waits to see what becomes of the man who led the island since the 1959 communist revolution, the institutions of Cuba's totalitarian system are in a period of negotiation over power-sharing duties.

The assistant secretary of state says the United States has a role to play in helping steer Cuba towards democracy, but it is a role that must be played from the sidelines.

"Cuba's future has to be determined by the Cuban people," he added. "Ultimately, no political solution can be imposed from the outside. It is imperative that the Cuban people be able to choose their future."

Shannon reiterated the Bush administration's position that the United States would move to reestablish diplomatic ties with Havana and drop the long-standing U.S. trade embargo against Cuba if and when genuine democracy takes hold on the island. He also said that an end to totalitarianism would allow Cuba to rejoin the Organization of American States, and to better integrate itself with the region and the international community as a whole.

But he admitted that just what choice the Cuban people ultimately make is difficult to predict, and that a thunderous clamoring for sweeping political change has yet to be heard on the island.

"Obviously, political openings and democratizations can take a variety of forms," he explained. "And we would be very interested in hearing from the Cubans themselves about how they envision that happening, if they envision it at all. The initial comments that we have received [from Cubans] do not seem to indicate a whole lot of interest, but we [the United States] are listening."

Since Fidel Castro ceded power to his brother, the Cuban government has encouraged citizens to mount public displays of their commitment to then island's communist system. Extra security forces have been deployed in Havana and elsewhere, but no political unrest has been reported.

Cuban authorities say they expect Fidel Castro to return to presidential duties in a matter of weeks or months.